Prior art magnetic heads are disclosed in U.S. Pat. No. 6,947,256 (“'256 patent”), titled “Embedded Wire Planar Write Head System and Method,” issued to Biskeborn, Doscher, and Eaton, U.S. Pat. No. 7,322,096 (“'096 patent”), which is a divisional of the '256 patent, also titled “Embedded Wire Planar Write Head System and Method,” and issued to Biskeborn, Doscher, and Eaton, and U.S. Pat. No. 7,119,976 (“'976 patent”), titled “Planar Servo Format Verifier Head,” issued to Biskeborn, Kirschenbaum, and Taylor. A characteristic of these prior art heads is beginning fabrication of the head with a trenched substrate, the trench being made into a nonmagnetic substrate, and the fabrication of the head proceeding thereupon with thin film processing. The trenched substrate is subsequently filled in so that the final plane of the recording head is substantially close to the plane of the originating substrate with the trench being filled in with much of the head structure.
FIGS. 1A and 1B illustrate a prior art magnetic write head of the type disclosed in the '256 patent. The '256 patent discloses building a head from a substrate 406 into which a trench has been made. For the single gap set head 400, the head is fabricated by depositing thin film layers into the trench. For each set of gaps 500, made up of arrays of discrete gaps 411 and 413 spanning the width of the tape, there is a single coil layer 410 running beneath the set of gaps 500. The coil layer 410 spans from one edge of the head to the other, parallel to the tape bearing surface, but the longitudinal axis and current flow of the coil layer 410 is perpendicular to the tape's velocity direction.
In FIGS. 2A and 2B, the '256 patent further illustrates tandem head structures 900 and 1200 made from two pockets patterned into the insulating layer in a single trench 906. This embodiment has two coils, one for each pocketed head element 902, 904 (FIG. 2A) or 1202, 1204 (FIG. 2B). This embodiment allows for two head elements 902, 904 (FIG. 2A) or 1202, 1204 (FIG. 2B), each of which are functionally identical to single head element 400 but which are displaced in the down-track direction with respect to each other. Each of the two coil layers, i.e., 1208, 1210, drives a uniquely associated set of gaps, i.e., write gaps 1206 of first head element 1202 and write gaps 1206 of second head element 1204, respectively, that are staggered from one another in the down-track direction to accommodate the necessary conducting circuit 1208, 1210 that spans from one end of the slider to the other, beneath the associated gap set.
In FIG. 2C, the '256 patent illustrates another embodiment 1000 based on a further down-track staggered gap and down-track staggered coil expansion of embodiment 900. In this embodiment 1000, a generalization of embodiment 900 is called out so that more gaps 1004 can be driven independently. In all of the above embodiments, the gaps are shown to be driven by a coil layer that spans from one edge of the slider to the other, each coil driving an associated set of gaps and each coil starting on one end of the slider body and ending on the other end. In the generalized embodiment, the gaps 1004 are aligned in a staggered formation to accommodate the necessary conducting circuits, and magnetic circuit, one circuit for each gap or gap set, and hence the gaps can only be written independently if they are staggered to accommodate the associated magnetic circuit and associated electrical conducting circuit.
The '096 patent further discloses and teaches the same subject matter as the above described planar head built from a trenched substrate. The '976 patent discloses a second trench for accommodation of the lead for a servo read head element and a formatting system for using such a head. This prior art embodiment is illustrated in FIG. 3.
The prior art only teaches planar heads built from a trenched substrate. Trenched substrate based heads lead to a natural result of air skiving edged, flat contour sliders that are velocity independent. However, the limited multichannel embodiments of the prior art have fabrication limitations and interconnect issues that are not fully addressed. In the independently written multi-channel embodiments, each channel is a full width trench head that is merely displaced in the down-track direction from one another. As such, seventeen such channels, for example, would require seventeen trenched heads displaced sixteen times in the down-track direction from one another. The resulting head-to-media interface would have an extremely wide media scrub zone that would mitigate the elegance of the air skiving single trench head.
Thus, there exists a need in the art for an easily manufactured planar magnetic head, particularly for tape servo format writing and verification, and more particularly for multi-channel embodiments with a narrow scrub path single bump interface. There is a need in the art for a method of making a planar magnetic head using a built-up approach on planar substrate, as opposed to deposition and lithography in a trenched substrate, to achieve a true planar head. There is a further need in the art for a method of making a planar magnetic head using thru-hole via technology to connect the leads to a conductive coil layer. There is a further need in the art for an easily manufactured planar magnetic head having independent channels without each gap set having to be displaced or staggered in the down-track direction.